GLOSSARY. 109 



Plu'mulae (L. little feathers). The fine feathers or down of 



birds. 

 Plu'mule (L. plumula, a little feather). The first bud of the 



embryo plant. 

 Pneumatic (Gr. pneuma, pneumatos, air). Containing air, as 



some bones of birds and other animals do. 

 Pneuma'tophore (Gr. pneuma, pneumatos, air ; phoreo, I bear). 



A kind of float formed in some Hydrozoa by a sac 



containing air, which is developed from one extremity of 



the hydrosoma. 



Pneumogas'tric ") (Gr. pneumon, the lungs ; gaster, the sto- 

 Pneumogas'trici j mach). A term applied to the tenth pair 



of cerebral nerves, because distributed, amongst other parts, 



to the lungs and stomach. 

 Pneumo'nia (Gr. pneumon, the lungs). Inflammation of the 



lungs. 

 Po'dical (L. podex, podicis, the fundament). Applied to two 



triangular plates, one situated on each side of the anus, in 



some Insecta. 

 Podophthal'mia (Gr. pous, podos, a foot ; ophthalmos, an eye). 



A division of the Crustacea in whicji the eyes are supported 



on long foot-stalks. 

 Podophthal'mite (Gr. pous, podos, a foot ; ophthalmos, an eye). 



The terminal joint of the eye-stalk in the Podophthalmia. 

 Podu'ridae (Gr. pous, podos, a foot ; our a, a tail). A group of 



insects in which the tail is used as a locomotive organ. 

 Pd'lian ve'sicles. Caecal prolongations given off by the circular 



ambulacral vessel in the Holothuridea. 

 Pollen (L. fine flour). The fine powdery matter contained 



within the anther, and which is necessary for the fertiliza- 

 tion of the ovules. 



Pollen tube. A long process from a pollen grain which ex- 

 tends itself down through the style till it reaches an ovule. 

 Pollex (L. thumb). The first digit of the manus, which in 



man is commonly termed the thumb. 

 Polychae'ta (Gr. pdlus, many ; chaite, long flowing hair). A 



group of the Annelida having the segments of the body 



usually abundantly supplied with strong setae. 

 Polycis'tina (Gr. polus, many ; kustis, a bladder). A group of 



Protozoa with minute perforated shells. 

 Polygas'trica (Gr. polus, many ; gaster , a stomach). The name 



given by Ehrenberg to the Infusoria. 

 Polyhe'dral (Gr. polus, many; hedra, a seat). Many-sided. 



